Lock assembly for ground engaging tool

ABSTRACT

A locking assembly for locking a ground engaging tool such as a shroud to a bucket lip. The bucket lip has a C-shaped boss fixed thereto. The ground engaging tool has a recess to receive a lock, the recess having an opening which is shorter in axial length than the recess. The lock is arranged to pivot about the boss as the ground engaging tool is slid rearwardly relative to the bucket lip. When the lock is located entirely within the recess, it can be accessed through a rear tunnel and tightened to hold the assembly in place.

FIELD OF THE INVENTION

The present invention relates to a locking assembly for attachment of ground engaging tools to earthmoving equipment, such as the attachment of shrouds to excavator buckets.

BACKGROUND TO THE INVENTION

Buckets of excavating equipment are subject to significant abrasive wear during use. For this reason, replaceable ground engaging tools (GET) are located about the buckets in the areas most susceptible to wear. A number of different GET are used, including heel shrouds, lip shrouds, adaptors, wear plates, teeth and corner shrouds.

The connection of shrouds such as lip shrouds and wing shrouds to bucket edges has presented a consistent challenge, and there are many different systems currently available which seek to perform this task in an efficient manner. Many of the systems use a locking pin, which passes through a bore of the bucket. Such an arrangement has an inherent problem in that the provision of a bore weakens the bucket. In addition, locking pins have a tendency to bend in use, and removal of a bent locking pin may be difficult.

Other systems use a latching system. These are problematic in that there is usually no ability to adjust or tighten the connection, hence the shrouds are liable to become loose.

There are known systems which include a locking member arranged to be placed in compression in order to tighten the connection between shroud and bucket. In general, these systems require the GET to be located in approximately its final position before the lock can be applied. As such, the systems are unforgiving for human error and/or deterioration of parts due to wear.

The present invention seeks to provide a locking system for shrouds and similar GET which alleviates, at least in part, some of the above problems.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a locking assembly for locking a ground engaging tool to a bucket;

-   -   the bucket including a pivot surface oriented away from a         digging edge of the bucket;     -   the ground engaging tool including a lock receiving cavity, the         lock receiving cavity having an opening in an outer surface         thereof, the lock receiving cavity having an axial length, the         opening having an axial length less than that of the cavity,     -   the locking assembly including a lock, the lock having an         operating axis, the lock having a bucket engagement portion and         a GET engagement portion, the lock having an axial length         greater than that of the opening of the lock receiving cavity;     -   the ground engaging tool being moveable relative to the bucket         between:     -   a first position in which the lock can be positioned such that         the bucket engagement portion abuts the pivot surface of the         bucket and the GET engagement portion extends through the         opening of the receiving cavity; and     -   a second position in which the lock can locate within the lock         receiving cavity with the bucket engagement portion abutting the         pivot surface of the bucket and the GET engagement portion         abutting a bearing surface of the ground engaging tool.

The locking assembly is preferably arranged such that the lock is able to pivot about the pivot surface of the bucket as the ground engaging tool moves between its first position and its second position.

It is preferred that the lock is able to be extended in an axial direction between a release position and a locked position, the lock having an axial length when in the locked position greater than when in the release position.

It is preferred that the lock is arranged to bear against the pivot surface of the bucket and the bearing surface of the ground engaging tool in order to lock the bucket and the ground engaging tool in a fixed relationship.

In a preferred embodiment, the locking assembly includes a resilient member having an active portion arranged, in use, to locate between an upper wall of the lock receiving cavity and the lock, the active portion being compressible so as to provide a force to the lock acting away from the upper wall and a force to the upper wall acting away from the lock.

According to a second aspect of the present invention there is provided a locking assembly for locking a ground engaging tool to a bucket;

-   -   the bucket including a bearing surface oriented towards a         digging edge of the bucket;     -   the ground engaging tool including a lock receiving cavity, the         lock receiving cavity having a bearing surface facing away from         a wear end of the ground engaging tool;     -   the locking assembly including a lock, the lock having an         operating axis, the lock having a bucket engagement portion and         a GET engagement portion spaced along the operating axis;     -   the bucket engagement portion including a release bearing         surface oriented towards the GET engagement portion, and the GET         engagement portion including a release bearing surface oriented         towards the bucket engagement portion;     -   whereby, during release of the locking assembly, the lock can be         contracted along its operating axis such that the release         bearing surface of the bucket engagement portion bears against         the bearing surface of the bucket, and the release bearing         surface of the GET engagement portion bears against the bearing         surface of the lock receiving cavity.

It will be appreciated that contraction of the lock places the lock into tension, and urges the ground engaging tool away from the digging edge of the bucket.

It is preferred that the GET engagement portion includes a laterally extending collar on which the release bearing surface is located.

According to a third aspect of the present invention there is provided a ground engaging tool having a digging edge;

-   -   the ground engaging tool including a lock receiving cavity, the         lock receiving cavity having a first axial end oriented towards         the digging edge and a second axial end oriented away from the         digging edge, an axial length of the lock receiving cavity being         defined between the first axial and the second axial end;     -   the lock receiving cavity having an opening in an outer surface         thereof, the opening having an axial length less than that of         the cavity,     -   the lock receiving cavity including a front surface extending         from the first axial end of the lock receiving cavity to a front         edge of the opening, the front surface extending partially in         the axial direction, the front surface having an uppermost         portion which is angled at an angle between 20° and 40° relative         to the outer surface.

In use, the front surface may be arranged to locate above a boss affixed to an excavator bucket.

The lock receiving cavity may have a bearing surface at the second axial end thereof facing towards a wear end of the ground engaging tool;

-   -   the bearing surface having a reduced transverse dimension         relative to side walls of the receiving cavity.

It is preferred that the receiving cavity includes a spacer receiving portion having an increased transverse direction relative to side walls of the receiving cavity.

According to a fourth aspect of the present invention there is provided a bucket arranged to receive at least one ground engaging tool, the bucket including a boss arranged to associate with the ground engaging tool, the boss including a pivot surface oriented away from an edge of the bucket and a bearing surface oriented towards the edge of the bucket, the bearing surface being further from the bucket edge than the pivot surface.

According to a fifth aspect of the present invention there is provided a bucket arranged to receive at least one ground engaging tool, the bucket having a digging edge, the bucket including a boss arranged to associate with the ground engaging tool,

-   -   wherein the boss includes a first arm parallel to the digging         edge and at least one second arm parallel to the first arm and         spaced from the first arm in a direction perpendicular to the         digging edge.

Preferably the boss includes two second arms which are aligned in the same direction, and which are spaced from each other by a gap. The gap is preferably between 25% and 50% of the length of the first arm.

According to a sixth aspect of the present invention there is provided a lock for securing a ground engaging tool to a bucket, the lock having an operating axis, the lock having a bucket engagement portion and a GET engagement portion spaced along the operating axis,

-   -   wherein the bucket engagement portion includes a concave bearing         surface oriented away from the lock and a convex reverse surface         oriented towards the GET engagement portion.

The lock may include a main body portion having a narrow width portion narrower than the width of the bucket engaging portion. Preferably the narrow width portion is located between the bucket engaging portion and side walls of the main body portion.

The GET engagement portion may include an axial extension having an outer bearing face. Preferably, the outer bearing face is circular.

The GET engagement portion may include a release bearing surface oriented towards the bucket engagement portion.

It is preferred that the GET engagement portion includes a laterally extending collar on which the release bearing surface is located.

According to a seventh aspect of the present invention there is provided a method of locking a ground engaging tool to a bucket;

-   -   the bucket including a pivot surface oriented away from a         digging edge of the bucket;     -   the ground engaging tool including a lock receiving cavity, the         lock receiving cavity having an opening in an outer surface         thereof, the lock receiving cavity having an axial length, the         opening having an axial length less than that of the cavity,     -   the method including the steps of locating the ground engaging         tool on the edge of the bucket; moving the ground engaging tool         rearwardly until the lock receiving cavity locates above the         pivot surface; inserting a lock into the opening of the lock         receiving cavity until a bucket engagement portion of the lock         locates against the pivot surface; moving the ground engaging         tool rearwardly until the lock is able to pivot about the pivot         surface and locate entirely within the lock receiving cavity,         and tightening the lock such that a GET engagement portion of         the lock bears against a bearing surface of the ground engaging         tool.

Preferably, the method includes an additional step following pivoting of the lock and before tightening, the additional step being locating a resilient member within the lock receiving cavity such that an active portion of the resilient member locates between the lock and a front surface of the lock receiving cavity and is placed into compression on tightening of the lock.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings:

FIG. 1 is an exploded view of a locking assembly in accordance with the present invention;

FIG. 2 is a close view of a boss attached to an excavator from the locking assembly of FIG. 1 ;

FIG. 3 is a front view of a shroud being part of the locking assembly of FIG. 1 ;

FIG. 4 is a rear view of the shroud of FIG. 3 ;

FIG. 5 is an under view of a lock receiving cavity within the shroud of FIG. 3 ;

FIG. 6 is a top view of the lock receiving cavity of FIG. 5 ;

FIG. 7 is a cross section through the shroud of FIG. 3 ;

FIG. 8 is an exploded view of a lock and cover from the lock assembly of FIG. 1 ;

FIG. 9 is an assembled view of the lock of FIG. 8 ;

FIG. 10 is a cross section through the lock of FIG. 8 ;

FIG. 11 is an assembled view of the lock of FIG. 8 showing the cover attached;

FIGS. 12 to 15 are sequential perspectives of the locking assembly of FIG. 1 shown during preparation for locking;

FIG. 16 is a cross section through the locking assembly shown in the position of FIG. 15 ;

FIG. 17 is a partially cutaway perspective of the locking assembly of FIG. 1 shown during pivoting of the lock;

FIG. 18 is a cross section through the locking assembly shown in the position of FIG. 17 ;

FIG. 19 is a perspective of the locking assembly of FIG. 1 shown following pivoting of the lock;

FIG. 20 is a partially cut away view through the locking assembly shown in the position of FIG. 19 ;

FIGS. 21 and 22 are partially cut away views of the locking assembly of FIG. 1 shown during attachment of a cover.

FIG. 23 is a cross section through the locking assembly shown in the position of FIG. 22 ;

FIGS. 24 and 25 are partially cut away views through the locking assembly of FIG. 1 shown during tightening of the lock;

FIG. 26 is a perspective of the locking assembly of FIG. 1 when in a locked configuration.

FIG. 27 is a partially cut away side view through the locking assembly of FIG. 1 at the start of a disassembly process;

FIG. 28 is a partially cut away rear view through the locking assembly of FIG. 1 at the start of the disassembly process;

FIG. 29 is a perspective of the locking assembly of FIG. 1 prior to disassembly; and

FIG. 30 is a cross section of the locking assembly of FIG. 1 during disassembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the Figures, there can be seen a portion of an excavator bucket 10 having a digging edge 12, an inner face 14 and an outer face 16. A ground engaging tool (GET) being a shroud 50 is shown being attached about the digging edge 12, and locked into place using a lock 100.

The bucket 10 has a boss 20 fixed to the inner face 14 by suitable means such as welding. The boss 20 can be best seen in FIG. 2 .

The boss 20 is broadly C-shaped in plan view. It has a first or main arm 22 which is parallel to the digging edge 12, two side arms 24 which extend perpendicular to the main arm 22 in a direction away from the digging edge 12, and two second or return arms 26 which extend inwardly from the ends of the side arms 24. The return arms 26 are each about one third the length of the main arm 22, and are parallel to the main arm 22. The return arms 26 are thus separated by a gap 28 of about one third the length of the main arm 22. It is anticipated that the gap 28 could be between 25% and 50% of the length of the main arm.

The main arm 22 has an inner face 30 which is oriented towards the return arms 26 and the gap 28. The inner face 30 has a bevelled upper edge 32.

The return arms 26 each have an inner face 34 oriented towards the main arm 22; that is, oriented towards the digging edge 12.

The shroud 50 has a digging edge 52, an upper leg 54 arranged to locate against the inner face 14 of the bucket 10 and a lower leg 56 arranged to locate against the outer face 16 of the bucket 10. The upper leg 54 and lower leg 56 are separated by an inner wall 58 which is arranged, in use, to abut the digging edge 12 of the bucket 10.

The upper leg 54 has a bottom surface 60 arranged to abut the inner face 14 of the bucket 10, and an upper surface 62 facing away from the inner face 14 of the bucket 10.

A lock receiving aperture 64 is located within the upper leg 54. The lock receiving aperture 64 is located internally of the bottom surface 60. The lock receiving aperture 64 has an axial direction in line with that of the upper leg 54; that is, perpendicular to the digging edge 52. The lock receiving aperture 64 has a first axial end 65 oriented towards the digging edge 12 and a second axial end 67 oriented away from the digging edge 12. The lock receiving aperture 64 has laterally spaced side walls 66 which are perpendicular to the bottom surface 60.

At the first axial end 65 the lock receiving aperture 64 has a curved wall 68 which extends from the bottom surface 60 to the upper surface 62. The curved wall 68 tapers from the bottom surface 60 to the upper surface 62, commencing at an angle of about 70° relative to the bottom surface 60 and finishing at an angle of about 40° relative to the upper surface 62. The curved wall 68 acts as a front surface of the lock receiving aperture 64. It will be appreciated that the curved wall 68 extends in the axial direction through a distance about one-third that of the axial length of the lock receiving aperture 64.

The curved wall 68 has an uppermost portion 69, which is at an angle of about 40° relative to the upper surface 62. It is envisaged that this angle can usefully be between about 20° and about 60°.

At the second axial end 67 a rear wall 70 extends between the two side walls 66. An arched tunnel 72 extends from the lock receiving aperture 64 through to a rear of the upper leg 54. The arched tunnel 72 opens into the rear wall 70. At the opening of the tunnel 72 into the rear wall 70 is an arched wall 74 recessed from the rear wall 70. The arched wall 74 acts as a bearing surface, as will be described further below.

The lock receiving aperture 64 opens out onto the upper surface 62 of the upper leg 54 at a lock receiving opening 76. The lock receiving opening 76 is generally bordered by the side walls 66, the curved wall 68 and the rear wall 70.

It will be noted that the axial length of the lock receiving aperture 64, measured from the rear wall 70 at the second axial end 67 to the edge of the curved wall 68 at the bottom surface 60 (that is, the first axial end 65), is significantly larger than the axial length of the lock receiving opening 76, measured from the rear wall 70 to the edge of the curved wall 68 at the upper surface 62.

The lock receiving aperture 64 has a spacer receiving cavity 78 located forward of the rear wall 70. The spacer receiving cavity is formed by transverse slots within the side walls 66, effectively enlarging the transverse dimension of the lock receiving aperture 64 at the spacer receiving cavity 78. The spacer receiving cavity 78 is defined at its front edge by shoulders 80 which extend away from the side walls 66. The shoulders 80 are slightly convex, with an axis of curvature parallel to the digging edge 52.

Each side wall 66 has a cover receiving recess 82 located forward of the spacer receiving cavity 78.

The lock 100 is shown in FIGS. 8 to 11 . The lock 100 includes a main body portion 102 having a first axial end 104 and a second axial end 106. A central bore extends through the lock 100 from the second axial end 106 in an axial direction. A threaded bolt 108 is pinned within the central bore by a pin 110, and extends in an axial direction along an operating axis of the lock 100.

An internally threaded axial extension 112 extends through the central bore and finishes in a circular head 114 located outside the second axial end 106. The axial extension 112 is arranged to engage as a nut about the threaded bolt 108, such that rotation of the axial extension 112 about the threaded bolt 108 causes axial movement of the circular head 114 relative to the main body portion 102.

The circular head 114 has a circular outer bearing face 116. A tool receiving aperture 118 is located centrally of the outer bearing face 116 to enable tool-assisted rotation of the axial extension 112.

A spacer 120 is mounted onto the axial extension 112 between the main body portion 102 of the lock and the circular head 114. The spacer 120 extends laterally wider than the main body portion 102, acting as a laterally extending collar. The spacer 120 is curved about an axis transverse to that of the lock 100, being concave on a bearing face 122 oriented towards the main body portion 102, and convex on an outer face 124 oriented towards the circular head 114. The curvature of the spacer 120 is the same as that of the spacer receiving cavity 78 in the shroud 50.

The first axial end 104 of the main body portion 102 includes a central portion 130 extending axially from an inner end of the bore to the first axial end 104, and two wings 132, with one wing 132 mounted on each transverse side of the central portion 130. The wings 132 are broadly kidney shaped in cross section, with a concave bearing surface 134 oriented away from the lock 100, and a convex reverse surface 136 oriented towards the spacer 120.

The wings 132 and central portion 130 between them, at the first axial end 104 of the main body portion 102, constitute a bucket engagement portion of the lock 100. The circular head 114 and spacer 120 constitute a GET engagement portion of the lock 100.

The main body portion 102 includes side walls 138. The side walls 138 define a width of the main body portion 102 which is about the same as the width between outer faces of the wings 132. The central portion 130 has side walls which define a narrower width than that of the side walls 138. In this way the main body portion 102 has a narrower width portion 140 adjacent the wings 132.

A cover 150 is used in conjunction with the lock 100. The cover 150 is made of a resilient material such as rubber. The cover 150 includes a body portion 152 arranged to locate, in use, atop the main body portion 102 of the lock 100. Two arms 154 extend downwardly from the body portion 152, arranged to locate on either side of the main body portion 102 of the lock 100.

At a forward end of the cover 150 a tab 156 extends away from the body portion 152. The tab 156 is arranged to locate over the central portion 130 at the first axial end 104 of the lock 100, between the wings 132.

Operation of the locking assembly will now be described. As can be seen in FIG. 12 , the operation required is to lock the shroud 50 onto the bucket 10. The first action is to position the shroud 50 over the digging edge 12 until the lock receiving aperture 64 is located over the boss 20. This can be seen in FIG. 13 .

It will be appreciated that in this position the boss 20—in particular the main arm 22—can be readily accessed through the lock receiving aperture 64 via the lock receiving opening 76.

As shown in FIG. 14 , the lock 100 is lowered through the lock receiving opening 76 with its first axial end 104 oriented towards the boss 20, until the point where the concave bearing surfaces 134 of the wings 132 locate against the bevelled upper edge 32 of the inner face 30 of the main arm 22. This final position can be seen in FIGS. 15 and 16 .

The shroud 50 can then be moved further over the bucket 10 so that the inner wall 58 of the shroud 50 approaches the digging edge 12 of the bucket 10. As this happens the lock 100 is permitted to pivot about the bevelled upper edge 32 of the main arm 22, with the curved wall 68 moving over the first axial end 104 of the lock 100. The shroud 50 is moved rearwardly until the spacer receiving cavity 78 reaches the spacer 120 of the lock 100. This is shown in FIGS. 17 and 18 . The bevelled upper edge 32 and inner face 30 of the main arm 22 serve as a pivot surface.

The lock 100 is then able to fall entirely into the lock receiving aperture 64, as shown in FIGS. 19 and 20 . Each wing 132 of the lock 100 locates between the main arm 22 and a return arm 26 of the boss 20. The central portion 130 of the lock 100 passes through the gap 28 in the boss 20. The spacer 120 of the lock 100 locates in the spacer receiving cavity 78. The circular head 114 of the axial extension 112 locates adjacent the arched wall 74 at the rear of the lock receiving aperture 64, with the tool receiving aperture 118 able to be accessed via the arched tunnel 72.

The cover 150 is then oriented above the lock 100 as shown in FIG. 21 , and pressed into position as shown in FIGS. 22 and 23 , with the tab 156 locating between the central portion 130 of the lock 100 and the curved wall 68 of the shroud 50, and the arms 154 extending down the sides of the main body portion 102, in the cover receiving recesses 82.

Rotation of the axial extension 112 of the lock 100 can be achieved through use of a tool passed through the arched tunnel 72 and into the tool receiving aperture 118. Rotation causes the circular head 114 to move away from the main body portion 102, thus increasing the effective axial length of the lock 100. The outer bearing face 116 contacts the arched wall 74, and then bears against the arched wall 74 to urge the shroud 50 rearwards until the inner wall 58 of the shroud 50 is forced against the digging edge 12 of the bucket 10. It will be appreciated that the lock 100 is in compression, between a bearing surface of the bucket (the inner face 30) and a bearing surface of the shroud (the arched wall 74).

During this tightening process the curved wall 68 is pulled rearwardly over the tab 156 of the cover 150. This squeezes the tab 156, placing it into compression, and thus creating an active portion which urges the lock 100 towards the inner face 14 of the bucket 10, and urging the curved wall 68 away from the inner face 14 of the bucket 10. This provides a moment acting about the digging edge 12, and thus urges the lower leg 56 of the shroud 50 against the outer face 16 of the bucket 10. This is shown in FIG. 25 .

As can be seen in FIGS. 24 and 25 , the tightening of the lock 100 causes the spacer 120 and the spacer receiving cavity 78 to move away from the main body portion 102, creating a small gap between them.

FIG. 26 shows the assembly in a fully locked and tightened configuration.

When the shroud 50 is to be removed from the bucket 10, the axial extension 112 of the lock 100 is rotated in the opposite direction to reduce the axial length of the lock 100. During this operation the bearing face 122 of the spacer 120 becomes a release bearing surface, acting against the shoulders 80 of the spacer receiving cavity 78 which becomes a bearing surface of the shroud 50. This is shown in FIG. 28 . At the same time the reverse surfaces 136 of the wings 132 become release bearing surfaces, acting against the return arms 26 of the boss 20 which become a bearing surface of the bucket 10.

It will be appreciated that this places the lock 100 into tension, and results in the spacer 120 urging the shroud 50 forwards and away from the digging edge 12.

When the shroud 50 has been thus urged away from the digging edge 12 and the lock 100 returned to a neutral and loose state, as shown in FIG. 29 , the cover 150 can be readily removed. A prybar 180 can then be inserted into the arched tunnel 72 as shown in FIG. 30 to raise the rear end of the lock 100 and allow it to be removed.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. 

1. A locking assembly for locking a ground engaging tool to a bucket; the bucket including a pivot surface oriented away from a digging edge of the bucket; the ground engaging tool including a lock receiving cavity, the lock receiving cavity having an opening in an outer surface thereof, the lock receiving cavity having an axial length, the opening having an axial length less than that of the cavity, the locking assembly including a lock, the lock having an operating axis, the lock having a bucket engagement portion and a GET engagement portion, the lock having an axial length greater than that of the opening of the lock receiving cavity; the ground engaging tool being moveable relative to the bucket between: a first position in which the lock can be positioned such that the bucket engagement portion abuts the pivot surface of the bucket and the GET engagement portion extends through the opening of the receiving cavity; and a second position in which the lock can locate within the lock receiving cavity with the bucket engagement portion abutting the pivot surface of the bucket and the GET engagement portion abutting a bearing surface of the ground engaging tool, wherein the locking assembly is arranged such that the lock is able to pivot about the pivot surface of the bucket as the ground engaging tool moves between its first position and its second position.
 2. A locking assembly as claimed in claim 1, wherein the lock is able to be extended in an axial direction between a release position and a locked position, the lock having an axial length when in the locked position greater than when in the release position.
 3. A locking assembly as claimed in claim 1, wherein the lock is arranged to bear against the pivot surface of the bucket and the bearing surface of the ground engaging tool in order to lock the bucket and the ground engaging tool in a fixed relationship.
 4. A locking assembly as claimed in claim 1, wherein the locking assembly includes a resilient member having an active portion arranged, in use, to locate between an upper wall of the lock receiving cavity and the lock, the active portion being compressible so as to provide a force to the lock acting away from the upper wall and a force to the upper wall acting away from the lock.
 5. A locking assembly for locking a ground engaging tool to a bucket; the bucket including a bearing surface oriented towards a digging edge of the bucket; the ground engaging tool including a lock receiving cavity, the lock receiving cavity having a bearing surface facing away from a wear end of the ground engaging tool; the locking assembly including a lock, the lock having an operating axis, the lock having a bucket engagement portion and a GET engagement portion spaced along the operating axis; the bucket engagement portion including a release bearing surface oriented towards the GET engagement portion, and the GET engagement portion including a release bearing surface oriented towards the bucket engagement portion; whereby, during release of the locking assembly, the lock can be contracted along its operating axis such that the release bearing surface of the bucket engagement portion bears against the bearing surface of the bucket, and the release bearing surface of the GET engagement portion bears against the bearing surface of the lock receiving cavity.
 6. A locking assembly as claimed in claim 5, wherein the GET engagement portion includes a laterally extending collar on which the release bearing surface is located.
 7. A ground engaging tool having a digging edge; the ground engaging tool including a lock receiving cavity, the lock receiving cavity having a first axial end oriented towards the digging edge and a second axial end oriented away from the digging edge, an axial length of the lock receiving cavity being defined between the first axial and the second axial end; the lock receiving cavity having an opening in an outer surface thereof, the opening having an axial length less than that of the cavity, the lock receiving cavity including a front surface extending from the first axial end of the lock receiving cavity to a front edge of the opening, the front surface extending partially in the axial direction, the front surface having an uppermost portion which is angled at an angle between 20° and 40° relative to the outer surface.
 8. A ground engaging tool as claimed in claim 7 wherein, in use, the front surface is arranged to locate above a boss affixed to an excavator bucket.
 9. A ground engaging tool as claimed in claim 7, wherein the lock receiving cavity may have a bearing surface at the second axial end thereof facing towards a wear end of the ground engaging tool; the bearing surface having a reduced transverse dimension relative to side walls of the receiving cavity.
 10. A ground engaging tool as claimed in claim 7, wherein the receiving cavity includes a spacer receiving portion having an increased transverse direction relative to side walls of the receiving cavity.
 11. A bucket arranged to receive at least one ground engaging tool, the bucket including a boss arranged to associate with the ground engaging tool, the boss including a pivot surface oriented away from an edge of the bucket and a bearing surface oriented towards the edge of the bucket, the bearing surface being further from the bucket edge than the pivot surface.
 12. A bucket arranged to receive at least one ground engaging tool, the bucket having a digging edge, the bucket including a boss arranged to associate with the ground engaging tool, wherein the boss includes a first arm parallel to the digging edge and at least one second arm parallel to the first arm and spaced from the first arm in a direction perpendicular to the digging edge.
 13. A bucket as claimed in claim 12, wherein the boss includes two second arms which are aligned in the same direction, and which are spaced from each other by a gap.
 14. A bucket as claimed in claim 13, wherein the gap is between 25% and 50% of the length of the first arm.
 15. A lock for securing a ground engaging tool to a bucket, the lock having an operating axis, the lock having a bucket engagement portion and a GET engagement portion spaced along the operating axis, wherein the bucket engagement portion includes a concave bearing surface oriented away from the lock and a convex reverse surface oriented towards the GET engagement portion.
 16. A lock as claimed in claim 15, wherein the lock includes a main body portion having a narrow width portion narrower than the width of the bucket engaging portion.
 17. A lock as claimed in claim 16, wherein the narrow width portion is located between the bucket engaging portion and side walls of the main body portion.
 18. A lock as claimed in claim 15, wherein the GET engagement portion includes an axial extension having an outer bearing face.
 19. A lock as claimed in claim 18, wherein the outer bearing face is circular.
 20. A lock as claimed in claim 15, wherein the GET engagement portion includes a release bearing surface oriented towards the bucket engagement portion.
 21. A lock as claimed in claim 20, wherein the GET engagement portion includes a laterally extending collar on which the release bearing surface is located.
 22. A method of locking a ground engaging tool to a bucket; the bucket including a pivot surface oriented away from a digging edge of the bucket; the ground engaging tool including a lock receiving cavity, the lock receiving cavity having an opening in an outer surface thereof, the lock receiving cavity having an axial length, the opening having an axial length less than that of the cavity, the method including the steps of locating the ground engaging tool on the edge of the bucket; moving the ground engaging tool rearwardly until the lock receiving cavity locates above the pivot surface; inserting a lock into the opening of the lock receiving cavity until a bucket engagement portion of the lock locates against the pivot surface; moving the ground engaging tool rearwardly until the lock is able to pivot about the pivot surface and locate entirely within the lock receiving cavity, and tightening the lock such that a GET engagement portion of the lock bears against a bearing surface of the ground engaging tool.
 23. A method of locking a ground engaging tool to a bucket as claimed in claim 22, wherein the method includes an additional step following pivoting of the lock and before tightening, the additional step being locating a resilient member within the lock receiving cavity such that an active portion of the resilient member locates between the lock and a front surface of the lock receiving cavity and is placed into compression on tightening of the lock. 